Retrievable setting tool for well plugs

ABSTRACT

The present disclosure relates to a well plug setting tool having a retrievable dog assembly, which replaces a mule shoe structure used in a state-of-the-art setting tool. The well plug setting tool according to the present disclosure reduces the amount of drillable or dissolvable material used for setting well plugs.

BACKGROUND Field

Embodiments of the present disclosure generally relate to a setting tool for well plugs. Particularly, embodiments of the present disclosure relate to a well plug setting tool with retrievable components and method for setting a well plug thereof.

Description of the Related Art

A well plug, such as a “frac” plug or a bridge plug, can be used to isolate one section of a wellbore from another section of the wellbore in various well operations. A well plug can be set in a tubular string, in which case the plug can isolate sections of the tubular string from one another.

Traditionally, a well plug is run-in and set in a location in the wellbore using a setting tool. The setting tool includes various components to apply setting forces on the well plug. After the well plug is set, the setting tool is retrieved from the wellbore while the well plug remains in the wellbore. Components of the well plug need to be dissolvable or be milled out after the well plug completes its operation.

Therefore, there exists the needs for improved setting tool and well plug design to reduce the amount of materials that need to be milled out or dissolve.

SUMMARY

Embodiments of the present disclosure generally relate to an apparatus and method for setting a well plug.

Embodiments for the present disclosure provide an apparatus for use in a wellbore. The apparatus includes a mandrel including a first section and a second section, and a dog assembly movably coupled to the mandrel, wherein the dog assembly comprises two of more dog members, the first section of the mandrel is operable to receive and support the dog assembly at an extended arrangement, and the second section of the mandrel is operable to receive and support the dog assembly in a retracted arrangement.

Some embodiments of the present disclosure provide an apparatus for use in a wellbore comprising a mandrel, a dog assembly disposed on the mandrel, wherein the dog assembly is movable along the mandrel between an extended arrangement and a retracted arrangement, and a cover sleeve assembly coupled to the mandrel, wherein the cover sleeve assembly is operable to move the dog assembly along the mandrel.

Some embodiments of the present disclosure provide a method for setting a well plug. The method includes applying a setting force to the well plug through a dog assembly while positioning the dog assembly in an extended arrangement on a first section of a mandrel, moving the dog assembly away from the first section of the mandrel to disengage the dog assembly from the well plug, and retrieving the mandrel with the dog assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the implementations, briefly summarized above, may be had by reference to implementations, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary implementations of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective implementations.

FIG. 1A is a schematic sectional view of a well system including a setting tool according to embodiments of the present disclosure.

FIG. 1B is a schematic sectional view of the well system of FIG. 1A during retrieval of the setting tool.

FIG. 2 is a schematic exploded view of a setting tool according to embodiments of the present disclosure.

FIGS. 3A-3C are schematic views of a mandrel in the setting tool of FIG. 2.

FIGS. 4A-4H are schematic views of a dog assembly in the setting tool of FIG. 2.

FIG. 5 is a schematic view of a cover sleeve assembly in the setting tool of FIG. 2.

FIG. 6A is a schematic view of a well system including a setting tool according to the present disclosure in a run-in position.

FIG. 6B is a schematic view of the well system of FIG. 6A in a well plug setting position.

FIG. 6C is a schematic view of the well system of FIG. 6A in a well plug disengagement position.

FIG. 6D is a schematic view of the well system of FIG. 6A in a dog assembly retracting position.

FIG. 6E is a schematic view of the well system of FIG. 6A in a pulling out position.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation. It is to be noted, however, that the appended drawings illustrate exemplary implementations of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective implementations.

DETAILED DESCRIPTION

The following disclosure describes well plug setting tools with a retrievable dog assembly. Details are set forth in the following description and in FIGS. 1A-6E to provide a thorough understanding of various implementations of the disclosure. Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular implementations. Accordingly, other implementations can have other details, components, dimensions, angles and features without departing from the spirit or scope of the present disclosure. In addition, further implementations of the disclosure can be practiced without several of the details described below.

Embodiments of the present disclosure generally relate to an apparatus utilized and operations performed in conjunction with a subterranean well. Particularly, embodiments of the present disclosure relate to a well plug setting tool and method for setting a well plug using the well plug setting tool. The well plug setting tools according to the present disclosure include a retrievable dog assembly, which replaces a mule shoe used in state-of-the-art setting tools. As a result, components that do not have a function after the well plug is set will be retrieved and reused.

FIG. 1A is a schematic sectional view of a well system 100 including a setting tool 120 according to the present disclosure. FIG. 1B is a schematic sectional view of the well system 100 during retrieval of the setting tool 120.

The well system 100 is merely one example of applications of the principles of this in practice, and a wide variety of other examples are possible. Therefore, the scope of this disclosure is not limited to the details of the well system 100 and method described herein and/or depicted in the drawings.

In the well system 100, a wellbore 102 penetrates an earth formation 104. The wellbore 102 is lined with casing 106. The casing 106 is secured in the earth formation 104 by cement 108. Even though the wellbore 102 is shown vertical in FIG. 1A, the wellbore 102 could be horizontal or otherwise deviated relative to vertical. The principles of this disclosure may be practiced in an uncased or open hole section of the wellbore 102 where the casing 106 is not present.

In FIG. 1A, a well plug 110 is coupled to the setting tool 120 according to the present disclosure. The setting tool 120 with the well plug 110 is conveyed to a target location in the wellbore 102. At the target location, the well plug 110 is first set to isolate upper and lower sections of the wellbore 102 from each other, and then the setting tool 120 is disengaged from the well plug 110 and retrieved back. The setting tool 120 may be conveyed by wireline, coiled tubing, or another type of conveyance. In FIG. 1A, the well plug 110 is directly attached to the setting tool 120. In other examples, a setting tool adapter (not shown) may be used to connect a well plug to the setting tool 120.

The well plug 110 shown in FIG. 1A includes a slip assembly 112 and a slip cone 114 movably coupled to the slip assembly 112. The slip assembly 112 has an inclined surface 113 for interacting with the slip cone, and a setting surface 117 for interacting with a setting tool. In some embodiments, the setting surface 117 is an inclined surface. In other embodiments the setting surface 117 is a flat surface substantially perpendicular to a central axis of the slip assembly 112. The slip assembly 112 may include inserts 116 disposed on an outer surface 111 to engage with wellbore surface when set. The inserts 116 are configured to secure the well plug 110 against longitudinal displacement relative to the wellbore 102. The slip cone 114 has an inclined surface 115 matching the inclined surface 113 of the slip assembly 112. In some embodiments, the slip cone 114 is a unitary component. To set the well plug 110, the slip cone 114 moves towards the slip assembly 112 along the inclined surfaces 113, 115 outwardly deflecting the slip assembly 112 until the inserts 116 engages with the inner surface of the wellbore.

In some embodiments, the slip assembly 112 may also include restraint element 118. The restraint element 118 is operable to prevent the well plug 110 from premature setting by presenting relative movement of the slip assembly 112 and the slip cone 114. In some embodiments, the restraint element 118 includes one or more shear pins positioned to secure the slip assembly 112 to the slip cone 114 at a pre-set position.

The well plug 110 is merely an example of a well plug. Any suitable well plugs may be used with principles of the present disclosure. For example, the well plug 110 may further include one or more sealing elements, such as elastomeric members, that expand outwardly to sealingly engage with the wellbore 102. The well plug 110 may be a composite plug, a dissolvable plug, a drillable plug, or combinations thereof.

The setting tool 120 includes a mandrel 122 supports and conveys a well plug, such as the well plug 110, near an upper end of the mandrel 122 during operation. A dog assembly 124 is coupled to the mandrel 122. The dog assembly 124 is positioned downwardly or at a lower end of the wellbore 102 relative to the well plug 110 on the mandrel 122. The dog assembly 124 is configured to support the well plug 110 and apply a setting force to the well plug 110 during operation. The setting tool 120 further includes a cover sleeve assembly 126. The cover sleeve assembly 126 is configured to facilitate the movement of the dog assembly 124 along the mandrel 122.

The setting tool 120 further includes an inner setting rod 128 and an outer setting sleeve 130. The inner setting rod 128 is connected to the mandrel 122. The outer setting sleeve 130 is connected to the well plug 110 on the mandrel 122. The inner setting rod 128 and the outer setting sleeve 130 may be connected to an actuator (not shown) configured to produce setting forces. The setting forces may be generated in a variety of ways, including ignition of a propellant, hydraulic, electrical or mechanical actuation, and the like. Thus, the scope of this disclosure is not limited to use of any particular type of actuators to apply the setting forces to the well plug 110.

When actuated, the actuator produces opposing longitudinal setting forces. In some embodiments, the actuator generates a compressive setting force 132 and a tensile setting force 134. The compressive setting force 132 is applied to the outer setting sleeve 130. The outer setting sleeve 130 then conveys the compressive setting force 132 to the well plug 110 in the form of a setting force 136. The tensile setting force 134 is applied to the inner setting rod 128. The inner setting rod 128 then conveys the tensile setting force 134 through the mandrel 122 and the dog assembly 124 to the well plug 110 in form of a setting force 138.

The oppositely directed setting forces 136, 138 act together to compress the well plug 110 along the longitudinal direction. Under the compression, the slip cone 114 moves into the slip assembly 112 along the inclined surfaces 113, 115. The slip assembly 112 expands along the radial direction into gripping engagement with the casing 106.

The cover sleeve assembly 126 is movably coupled to the mandrel 122. The cover sleeve assembly 126 and the well plug 110 are positioned on opposite sides of the dog assembly 124. During run-in and setting, the cover sleeve assembly 126 is in the position to secure the dog assembly 124 in a run-in location of the mandrel 122, as show in FIG. 1A. After the well plug 110 is set and engaged with the wellbore 102, the cover sleeve assembly 126 moves to facilitate transition of the dog assembly 124 from the run-in location to a retrieval location in the mandrel 122. During retrieval, the cover sleeve assembly 126 is in the position to secure the dog assembly 124 in the mandrel 122 as shown in FIG. 1B.

FIGS. 2-5 schematically describe details of the setting tool 120 according to the present disclosure. FIG. 2 is a schematic exploded view of the setting tool 120. FIGS. 3A-3C are schematic views of the mandrel 122 in the setting tool 120. FIGS. 4A-4H are schematic views of the dog assembly 124 in the setting tool 120. FIG. 5 is schematic views of the cover sleeve assembly 126 in the setting tool 120.

As depicted in FIG. 2, a well plug to be set and components of the setting tool 120 are assembled along the mandrel 122. The mandrel 122 is a substantially cylindrical shape. In some embodiments, the mandrel 122 is a solid cylindrical component including multiple sections of various outer diameters or profiles. The multiple sections are operable to support and interact with different components.

In some embodiments, the mandrel 122 includes an upper end section 220, a plug section 224, a dog operating section 228, a dog retrieval section 234, and a cover sleeve section 236, and a lower end section 238. The plug section 224 is configured to receive a well plug, such as the well plug 110. The dog operating section 228 and the dog retrieval section 234 are configured to receive and support the dog assembly 124 during setting and retrieval operations respectively. The cover sleeve section 236 and the lower end section 238 are configured to couple with the cover sleeve assembly 126.

FIG. 3A is a schematic sectional view of the mandrel 122. Even though the mandrel 122 is shown as a one-piece component, it is within the principle of the present disclosure for the mandrel 122 to include two or more components assembled together as a design choice, for the ease of manufacturing or installation.

The upper end section 220 has the largest diameter of the mandrel 122. The upper end section 220 is configured to connect with an actuator. For example, the upper end section 220 may include an inner thread 302, shown in FIG. 3A, for connecting with the inner setting rod 128.

The plug section 224 is configured to receive a well plug, such as the well plug 110. An outer diameter 304 of the plug section 224 matches an inner diameter of the well plug 110. In some embodiments, the plug section 224 and the upper end section 220 are connected by a shoulder 222. The shoulder 222 may be used to prevent the well plug 110 on the plug section 224 from travelling upwards during operation. In some embodiments, during run-in, one or more components of the well plug 110 may be fixedly attached to the mandrel 122 at the plug section 224 by a shearable connection, such as by shear pins, to prevent the well plug 110 from premature setting.

As described above, the dog assembly 124 used to set the well plug 110 is retrievable. To enable retrieval, the dog assembly 124 is movable from the dog operating section 228 on the mandrel 122 to the dog retrieval section 234 on the mandrel. FIG. 3B is a schematic cross-sectional view of the mandrel 122 at the dog operating section 228. Two or more slots 230 are longitudinally formed on the mandrel 122 for receiving the dog assembly 124. FIG. 3C is a schematic cross-sectional view of the mandrel 122 at a part of the dog operating section 228 overlapping with the dog retrieval section 234.

The dog operation section 228 is connected to the plug section 224 by a shoulder 226. The dog operating section 228 includes two or more of slots 230 formed and circumferentially distributed on an outer surface 228 o of the dog operating section 228. In some embodiments, each slot 230 extends along the longitudinal direction in configured to receive one dog member 240 therein. In some embodiments, the two or more slots 230 may be evenly distributed circumferentially along the outer surface 2280. In other embodiments, the two or more slots 230 may be distributed non-evenly. When placed on the dog operating section 228 of the mandrel 122, the dog assembly 124 is in an extended arrangement.

The dog retrieval section 234 is configured to receive and support the dog assembly 124 during retrieval of the setting tool 120. When placed on the dog retrieval section 234 of the mandrel 122, the dog assembly 124 is in a retracted arrangement. The dog retrieval section 234 includes a cylindrical section having an outer diameter smaller than the dog operating section 228 to allow the dog assembly 124 to retract within an inner diameter of the well plug 110 during retrieval.

In some embodiments, the dog retrieval section 234 and the dog operating section 228 may overlap along the longitudinal direction of the mandrel 122 forming an annular wall 231. The annular wall 231 defines a recess 232 therein. The annular wall 231 may be used to retain at least a portion of the dog assembly 124 in the recess 232 to prevent the dog assembly 124 from falling out during retrieval. When positioned in the retracted arrangement, the dog assembly 124 is movable along the dog retrieval section 234. When the dog assembly 124 moves up the dog retrieval section 234, at least a portion of the dog assembly 124 is retained in the recess 232.

As shown in FIGS. 4A-4D, the dog assembly 124 includes two or more dog members 240. The two or more dog members 240 are circumferentially arranged about a central axis 401. The two or more dog members 240 move along radial directions relative so that the dog assembly 124 is extended or retracted. FIG. 4A is a schematic sectional view of the dog assembly 124 in an extended arrangement. FIG. 4B is a schematic sectional view of the dog assembly 124 in a retracted arrangement. The number of dog members 240 in the dog assembly 124 may be selected based on operating parameters and/or design choice. For example, the number of dog members 240 may be between 2 to 12, or other suitable numbers.

FIG. 4C is a schematic perspective view of the dog member 240 according to the present disclosure. FIG. 4D is a schematic sectional view of the dog member 240. Each dog member 240 may be formed from ridged materials, such as steel, to convey setting force from the mandrel 122 to the well plug 110. In some embodiments, the two or more dog members 240 may form a tubular body in the retracted arrangement. In the retracted arrangement as shown in FIG. 4B, the dog assembly 124 forms a tubular body having an outer diameter 408 and an inner diameter 406. The outer diameter 408 is smaller than the outer diameter 304 of the well plug section 224 of the mandrel 122. Because the outer diameter 304 matches the inner diameter of the well plug 110, the dog assembly 124 can be retrieved through the inner diameter of the well plug 110 after the well plug 110 is set. The inner diameter 406 matches the outer diameter of the dog retrieval section 234 of the mandrel 122 so that the dog assembly 124 can be secured around the dog retrieval section 234 during retrieval.

Each dog member 240 may include a base portion 402 shaped to allow the dog member 240 to be secured on and moved along the mandrel 122. In some embodiments, the base portion 402 is a section of a tubular. Each dog member 240 also includes a setting surface 410 and a backing surface 412. The setting surface 410 is configured to contact the well plug 110 and apply the setting force to the well plug 110. The backing surface 412 is configured to receive a backing force from the cover sleeve assembly 126. The setting surface 410 is configured to match a setting surface on a well plug, such as the setting surface 117 on the slip assembly 112 described above. In some embodiments, the setting surface 410 may have an incline to match an inclined setting surface on a well plug, for example when the setting surface 117 on the slip assembly 112 is an inclined surface. The incline on the setting surface 410 allows the setting force to move the slip assembly 112 radially outwards, thus, facilitating the setting of the well plug 110. Alternatively, the setting surface 410 is without an incline to match the profile of the well plug to be set.

In some embodiments, the setting surface 410 and the backing surface 412 may be formed on a protrusion 404 extended radially outward from the base portion 402. In some embodiments, the protrusion 404 has a fan shape when viewed along longitudinal direction to increase contact areas on the setting surface 410 and the backing surface 412 and improve strength of the dog member 240.

In some embodiments, the protrusion 404 is shorter than the base portion 402 forming a head 416 and a tail 414. During operation, the head 416 and the tail 414 allow the dog member 240 to be tugged under other tubular elements to secure the dog assembly 124.

In some embodiments, the dog assembly 124 further includes one or more retainers 242, 244. The retainers 242, 244 may be resilient members positioned around the two or more dog members 240 to bias the dog assembly 124 towards the retracted arrangement. In some embodiments, each dog member 240 may include one or more grooves 418, 420 for receiving the retainers 242, 244. In some embodiments, the grooves 418, 420 may be formed in the tail 414 and the head 416 respectively. In some embodiments, the retainers 242, 244 may be elastomeric rings. Other resilient elements, such as C-rings, may be used as retainers 242, 244.

The dog assembly 124 is movable on the mandrel 122 from the dog operating section 228 to the dog retrieval section 234. FIGS. 4E-4H are schematic views of the setting tool 120 showing the dog assembly 124 moving from the dog operating section 228 to the dog retrieval section 234.

Referring back to FIG. 2, the cover sleeve assembly 126 is movably attached to the mandrel 122 on the cover sleeve section 236 and the lower end section 238. The cover sleeve assembly 126 secures the dog assembly 124 on the dog operating section 228 during run-in and setting, facilitates the dog assembly 124 moving from the dog operating section 228 to the dog retrieval section 234 after setting, and retains the dog assembly 124 in the dog retrieval section 234 during retrieval. The cover sleeve assembly 126 also functions as a debris barrier to keep debris from the wellbore fluid from entering the setting tool.

In some embodiments, the cover sleeve assembly 126 includes a sleeve 260 configured to interact with the dog assembly 124, an end cap 266 fixedly attached to the mandrel 122 at the lower end section 238, and a resilient member 264 positioned between the end cap 266 and sleeve 260 to apply a bias therebetween. In some embodiments, the cover sleeve assembly 126 further includes a seal member 262 positioned between the sleeve 260 and the mandrel 122.

FIG. 5 schematically illustrates the cover sleeve assembly 126 in the run-in and setting position. The sleeve 260 is movably coupled to the cover sleeve section 236 of the mandrel 122. In the example of FIG. 5, the sleeve 260 has a step 502 in the inner surface. The step 502 creates a cavity 504 between the mandrel 122 and the sleeve 260. The cavity 504 extends from the step 502 to the end cap 266. The resilient member 264 is placed in the cavity 504. In some embodiments, the cavity 504 is an annular space. In some embodiments, the resilient member 264 connects the sleeve 260 and the end cap 266 to push and pull the sleeve 260 and move the sleeve 260 along the mandrel 122 during operation. In some embodiments, the resilient member 264 may be a helical spring, or any suitable resilient structures.

The seal member 262 is disposed between the mandrel 122 and the sleeve 260 to prevent debris from entering the setting tool 120. The seal member 262 may be a resilient sealing member, such as an elastomeric seal member, a C-ring or other suitable sealing solutions.

During run-in and setting, the sleeve 260 is fixedly attached to the mandrel 122. In some embodiments, one or more shearable elements 506 may be used to attach the sleeve 260 to the mandrel 122. The shearable elements 506 are designed to maintain the sleeve 260 stationary relative to the mandrel 122 until the well plug 110 is set. In some embodiments, the shearable elements 506 include one or more shear pins configured to withstand the force designed to set the well plug 110.

The setting tool 120 described above is used to set a well plug downhole, and is retrieved from the wellbore after setting the well plug. FIGS. 6A-6E schematically demonstrate the setting tool 120 at different stages during operation according to embodiments of the present disclosure.

Prior to run-in, the well plug 110 is first assembled onto the setting tool 120 to the run-in position, as shown in FIG. 6A. To assemble the setting tool 120 for run-in, the well plug 110 is first installed on the plug section 224 of the mandrel 122. The tubular components in the well plug 110 may be installed by moving the well plug 110 upward from the lower end section 238 of the mandrel 122. The slip cone 114 of the well plug 110 faces up to be in contact with the outer setting sleeve 130 during operation. The slip assembly 112 of the well plug 110 extends towards the dog operating section 228 of the mandrel 122. In some embodiments, to prevent pre-mature setting, components of the well plug 110 may be fixedly coupled to each other or to the mandrel 122 using temporary means, such as the restraint element 118.

The dog assembly 124 is then installed on the dog operating section 228 of the mandrel 122. The setting surface 410 of each dog member 240 is positioned against the slip assembly 112 of the well plug 110. The cover sleeve assembly 126 is then installed on the mandrel 122. The sleeve 260 is positioned against the backing surface 412 on the dog members 240. The sleeve 260 may be secured to the mandrel 122 by the shearable elements 506 to maintain contact with the dog members 240. In some embodiments, the resilient member 264 may be in an extended run-in position.

In FIG. 6A, the assembled setting tool 120 is run-in to a wellbore 602 lined by a casing 604 through a work string (not shown), such as a wireline, slickline or coiled tubing. FIG. 6B is a schematic view of the well system 600 in a well plug setting position. When the well plug 110 arrives at the target location, the compressive setting force 132 and tensile setting force 134 are dispatched to the setting tool 120. The setting forces 132, 134 are generated from an actuator attached to the setting tool 120. The setting forces 132, 134 may be produced in any of a variety of different ways, including ignition of a propellant, hydraulic, electrical or mechanical actuation, and the like.

As shown in FIG. 6B, the compressive setting force 132 travels through a transfer path including the outer setting sleeve 130 to the slip cone 114 as the setting force 136. The tensile setting force 134 travels through a transfer path, which includes the inner setting rod 128, the mandrel 122, the shearable elements 506, the sleeve 260, and the dog member 240, to the slip assembly 112 as the force 138. Under the setting forces 136, 138, the slip cone 114 moves into the slip assembly 112 pushing the slip assembly 112 radially outwards to engage with the casing 604. When a shearable connection, such as the restrain element 118, is used to secure the well plug 110 from premature setting, the setting forces 136, 138 need to overcome the rated force of the shearable connection before setting the well plug 110.

FIGS. 6C-6E schematically illustrate various stages of retrieving the setting tool 120 after the well plug 110 has been set to form an engagement with the inner surface of the wellbore 602, such as the casing 604. In FIG. 6C, the tensile setting force 134 is further increased to break the shearable elements 506. Once the shearable elements 506 are broken, the sleeve 260 is slidable on the mandrel 122. The mandrel 122 moves upwards under the tensile setting force 134 and pulls away from the well plug 110. The dog assembly 124, which is engaged with the slip assembly 112, slides along the slots 230 on the dog operating section 228 towards the dog retrieval section 234 while pushing the sleeve 260 towards the end cap 266.

In some embodiments, the resilient member 264 is in an extended state before the shearable connection 506 is broken. Once the shearable elements 506 are broken, the resilient member 264 pulls the sleeve 260 towards the end cap 266 at first. As the dog assembly 124 and the sleeve 260 further moves towards the end cap 266, the resilient member 264 becomes compressed.

In FIG. 6D, the dog assembly 124 slides off the dog operating section 228 and collapses to the retracted arrangement around the dog retrieval section 234 of the mandrel 122 under the restraint of the retainers 242, 244. In the retracted arrangement, the dog assembly 124, with the outer diameter 408 smaller than the inner diameter of the well plug 110, is no longer engaged with the well plug 110 but remains engaged with the sleeve 260. The sleeve 260 in connection with the compressed resilient member 264 pushes the dog assembly 124 upwards along the dog retrieval section 234.

In FIG. 6E, the dog assembly 124 is pushed upwards along the dog retrieval section 234 so that a portion of each dog member 240 is secured in the recess 232 defined by the annular wall 231. The annular wall 231 along with the retainers 242, 242 reduces or prevents radial movements of the dog member 240. The resilient member 264 via the sleeve 260 pushes the dog assembly 124 against the mandrel 122 to reduce or prevent movement of the dog assembly 124 on the mandrel 122 along the longitudinal direction. With the dog assembly 124 secured to the mandrel 122, the setting tool 120 can be retrieved.

The setting tool according to the present disclosure replaces the mule shoe structure used in state-of-the-art setting tools with a retrievable dog assembly, thus reducing the amount of drillable or dissolvable material used for setting well plugs. The setting tools with retrievable dog assembly not only lower the cost of wellbore operations, but also reduces undesirable debris in the wellbore fluid from dissolvable or drillable material.

Embodiments for the present disclosure provide an apparatus for use in a wellbore. The apparatus includes a mandrel including a first section and a second section, and a dog assembly movably coupled to the mandrel, wherein the dog assembly comprises two of more dog members, the first section of the mandrel is operable to receive and support the dog assembly at an extended arrangement, and the second section of the mandrel is operable to receive and support the dog assembly in a retracted arrangement.

In one or more embodiments, two or more slots are formed on the first section of the mandrel, and the two or more slots are operable to receive the two or more dog members and allow the two or more dog members to move relative to the mandrel along a longitudinal direction.

In one or more embodiments, the first section and the second section overlap to form an annular wall on the mandrel, and the annular wall defines a recess operable to retain a portion of the dog assembly.

In one or more embodiments, each of the two or more dog members includes a base and a protrusion, the protrusion includes an inclined surface operable to contact a well plug, and the recess is operable to receive the base of the dog members.

In one or more embodiments, the dog assembly further comprises a retainer disposed around the two or more dog members.

In one or more embodiments, the mandrel includes a third section operable to receive and support a well plug, and an outer diameter of the dog assembly in the retracted arrangement is smaller than an outer diameter of the third section of the mandrel.

In one or more embodiments, the apparatus further includes a sleeve movably coupled to the mandrel, and a resilient element connected to the sleeve and operable to bias the sleeve towards the dog assembly.

Some embodiments of the present disclosure provide an apparatus for use in a wellbore comprising a mandrel, a dog assembly disposed on the mandrel, wherein the dog assembly is movable along the mandrel between an extended arrangement and a retracted arrangement, and a cover sleeve assembly coupled to the mandrel, wherein the cover sleeve assembly is operable to move the dog assembly along the mandrel.

In one or more embodiments, the cover sleeve assembly functions as a debris barrier.

In one or more embodiments, the dog assembly comprises two or more dog members operable to apply a setting force towards a well plug to be set.

In one or more embodiments, the dog assembly further comprises at least one retainer disposed around the two or more dog members to bias the dog assembly towards the retracted arrangement.

In one or more embodiments, the two or more dog members are movable along the mandrel from a first section to a second section, the first section is operable to support the dog assembly in the extended arrangement, and the second section is operable to support the dog assembly in the retracted arrangement.

In one or more embodiments, the mandrel includes two or more slots formed on the first section, the two or more slots are operable to receive the two or more dog members, and the two or more dog members are slidable along the two or more slots.

In one or more embodiments, the first section overlaps with the second section to form an annular wall on the mandrel, and the annular wall is operable to retain a portion of the dog assembly when the dog assembly is in the retracted arrangement.

In one or more embodiments, the cover sleeve assembly includes a sleeve disposed around the mandrel and in contact with the dog assembly, and a resilient member disposed around the mandrel and operable to bias the sleeve towards the dog assembly.

Some embodiments of the present disclosure provide a method for setting a well plug. The method includes applying a setting force to the well plug through a dog assembly while positioning the dog assembly in an extended arrangement on a first section of a mandrel, moving the dog assembly away from the first section of the mandrel to disengage the dog assembly from the well plug, and retrieving the mandrel with the dog assembly.

In one or more embodiments, moving the dog assembly comprises increasing the setting force to break a shearable connection.

In one or more embodiments, moving the dog assembly comprises sliding the dog assembly along slots formed on the first section of the mandrel.

In one or more embodiments, the method further includes moving the dog assembly from the first section to a second section on the mandrel and positioning the dog assembly at a retracted arrangement around the second section.

In one or more embodiments, the method further includes moving the dog assembly along the second section to retain a portion of the dog assembly within an annular wall of the mandrel.

In one or more embodiments, moving the dog assembly along the second section comprises extending a compressed resilient member in connection with the dog assembly.

While the foregoing is directed to implementations of the present disclosure, other and further implementation of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. An apparatus for use in a wellbore, comprising: a mandrel including a first section and a second section; and a dog assembly movably coupled to the mandrel, wherein the dog assembly comprises two of more dog members, the first section of the mandrel is operable to receive and support the dog assembly at an extended arrangement, and the second section of the mandrel is operable to receive and support the dog assembly in a retracted arrangement.
 2. The apparatus of claim 1, wherein two or more slots are formed on the first section of the mandrel, and the two or more slots are operable to receive the two or more dog members and allow the two or more dog members to move relative to the mandrel along a longitudinal direction.
 3. The apparatus of claim 1, wherein the first section and the second section overlap to form an annular wall on the mandrel, and the annular wall defines a recess operable to retain a portion of the dog assembly.
 4. The apparatus of claim 3, wherein each of the two or more dog members includes a base and a protrusion, the protrusion includes an inclined surface operable to contact a well plug, and the recess is operable to receive the base of the dog members.
 5. The apparatus of claim 1, wherein the dog assembly further comprises a retainer disposed around the two or more dog members.
 6. The apparatus of claim 1, wherein the mandrel includes a third section operable to receive and support a well plug, and an outer diameter of the dog assembly in the retracted arrangement is smaller than an outer diameter of the third section of the mandrel.
 7. The apparatus of claim 1, further comprising: a sleeve movably coupled to the mandrel; and a resilient element connected to the sleeve and operable to bias the sleeve towards the dog assembly.
 8. An apparatus for use in a wellbore, comprising: a mandrel; a dog assembly disposed on the mandrel, wherein the dog assembly is movable along the mandrel between an extended arrangement and a retracted arrangement; and a cover sleeve assembly coupled to the mandrel, wherein the cover sleeve assembly is operable to move the dog assembly along the mandrel.
 9. The apparatus of claim 8, wherein the dog assembly comprises two or more dog members operable to apply a setting force towards a well plug to be set.
 10. The apparatus of claim 9, wherein the dog assembly further comprises at least one retainer disposed around the two or more dog members to bias the dog assembly towards the retracted arrangement.
 11. The apparatus of claim 9, wherein the two or more dog members are movable along the mandrel from a first section to a second section, the first section is operable to support the dog assembly in the extended arrangement, and the second section is operable to support the dog assembly in the retracted arrangement.
 12. The apparatus of claim 11, wherein the mandrel includes two or more slots formed on the first section, the two or more slots are operable to receive the two or more dog members, and the two or more dog members are slidable along the two or more slots.
 13. The apparatus of claim 12, wherein the first section overlaps with the second section to form an annular wall on the mandrel, and the annular wall is operable to retain a portion of the dog assembly when the dog assembly is in the retracted arrangement.
 14. The apparatus of claim 8, wherein the cover sleeve assembly comprises: a sleeve disposed around the mandrel and in contact with the dog assembly; and a resilient member disposed around the mandrel and operable to bias the sleeve towards the dog assembly.
 15. A method for setting a well plug, comprising: applying a setting force to the well plug through a dog assembly while positioning the dog assembly in an extended arrangement on a first section of a mandrel; moving the dog assembly away from the first section of the mandrel to disengage the dog assembly from the well plug; and retrieving the mandrel with the dog assembly.
 16. The method of claim 15, wherein moving the dog assembly comprises increasing the setting force to break a shearable connection.
 17. The method of claim 15, wherein moving the dog assembly comprises sliding the dog assembly along slots formed on the first section of the mandrel.
 18. The method of claim 15, further comprising moving the dog assembly from the first section to a second section on the mandrel and positioning the dog assembly at a retracted arrangement around the second section.
 19. The method of claim 18, further comprising moving the dog assembly along the second section to retain a portion of the dog assembly within an annular wall of the mandrel.
 20. The method of claim 19, wherein moving the dog assembly along the second section comprises extending a compressed resilient member in connection with the dog assembly. 